Yamaha’s all-terrain vehicles use a thumb-operated lever attached to the right handlebar to open and close the throttle valve within the machine’s carburetor or throttle body. The lever is attached to an enclosed housing, where a barrel-shaped fitting at the end of the throttle cable is kept safe from dirt and other elements. However, the throttle is not impervious to damage. Wear and tear can weaken the plastic lever and severe impacts can crack the throttle assembly open. Replacing a damaged throttle is not difficult, allowing most ATV owners to make repairs with only a small selection of tools.
1) Pull the rubber dust cover away from the rear of the throttle lever assembly, located on the right handlebar, to expose the throttle cable adjuster. Loosen the adjuster lock nut, using an open-end wrench.
2) Remove the cover from the top of the throttle assembly, using a Phillips screwdriver. Turn the throttle cable adjuster clockwise until it is seated against the throttle assembly housing to loosen the throttle cable. Pull the barrel-shaped cable end fitting out of the throttle lever catch, using needle-nose pliers.
3) Turn the cable adjuster counterclockwise until the cable can be pulled free from the throttle assembly.
4) Pull the plastic handlebar protector off the center of the handlebar, if equipped. Follow the throttle assembly’s electrical wiring lead, if any, to the connector near the center of the handlebar. Unplug the connector, then cut off any nylon cable ties attaching the wiring lead to the handlebar, using a razor blade.
5) Remove the throttle assembly from the right handlebar, using a Phillips screwdriver or a socket wrench. Clean the handlebar with a degreasing cleaner, then wipe dry with a shop towel.
6) Mount the new throttle assembly onto the right handlebar. Tighten the throttle mounting bolts to 2.9 foot-pounds, using a torque wrench.
7) Plug the throttle assembly wiring lead into its corresponding connector near the center of the handlebar. Secure the wiring lead to the handlebar, using nylon cable ties, then cut off the excess tie material. Push the handlebar protector into place.
8) Push the throttle cable end into the throttle assembly, then screw the cable adjuster into place until it is seated against the throttle assembly housing. Slip the cable end fitting into the throttle lever catch. Install the throttle assembly cover onto the throttle assembly.
9) Turn the throttle cable adjuster counterclockwise to tighten the cable. Push lightly on the throttle lever periodically to check the cable tension. Ideally, the throttle lever should have 1/8-inch of free movement before the throttle cable is pulled, indicated by a slight feeling of resistance. Tighten the adjuster lock nut against the throttle assembly once the throttle lever has 1/8-inch of free movement when pushed. Pull the rubber dust cover over the upper throttle cable adjuster.
* The throttle cable tension can be adjusted further using a second cable adjuster located near the carburetor throttle valve, usually placed behind a triangular cover on the right side of the carburetor. Only use this second adjuster if the throttle cable cannot be adjusted to provide 1/8-inch of free movement at the throttle lever using the cable adjuster near the throttle assembly.
* Always ensure that the throttle cable allows for some free movement within the throttle lever. An overly tightened throttle cable can cause the engine to rev while turning and is more prone to breakage.
For Yamaha ATV maintenance parts and more, check out our sponsor partspitstop.com